Читать книгу The Rise of the Flying Machine - Hugo Byttebier - Страница 26

Alexandre Goupil

One of the most able pioneers of that year was Alexandre Goupil. In an article published in July he too referred to the theme of the dirigible parachute. He stated that, contrary to some preconceived ideas, an aeroplane, when the engine stopped or failed, would not fall but would turn into a dirigible parachute. This is perfectly true, because aeroplanes, if they do not break up in the air, do not fall and if the engine fails, gravity takes over and the aeroplane becomes a glider as long as the pilot is able to control the descent by maintaining a flying speed above the minimum necessary for sustentation.

Goupil had gone thoroughly into the study of the fixed-wing aeroplane. He had experimented with a sort of kite weighing 50 kg (110 lbs) with a surface of 290 sq ft held against a wind of 6 m/s (14 mph) at an angle of 10 degrees, this kite was able to lift two men but at greater wind-speed the apparatus became uncontrollable and broke up.

Goupil had studied Mouillard’s book and was confident that the problems relating to human flight could be solved. But he was convinced that some form of mechanical power was needed and he designed a light steam engine which was calculated to develop 15 hp for a weight of 638 lbs.

The results of his studies and observations were condensed into a small book entitled La Locomotion aérienne, published in 1884, which is remarkable for the many solutions it provided to the difficulties that continued to beset the flight of a practical aeroplane.

In his book Goupil formulated a theory of flight and arrived at the same conclusions as Phillips, that a curved wing was the most efficient shape. He also explained that lift was obtained by the rarefaction of air above the wing, more than by the pressure built up under the wing. But whereas Philips’ conclusions were the result of experimental work, those of Goupil, like those of many French scientists, were based on mathematical theories.

It was clear to Goupil that fixed-wing aeroplanes would need large fields “devoid of trees” because the angle of climb after take-off would be small; and an aeroplane would have to take off heading into the wind. All this was close to the realities of human flight and nobody will argue about the need for large airfields today.

Goupil’s aeroplane project was to be made laterally stable by a dihedral angle of the wing, as Cayley had already proposed, but due to the influence of Mouillard, no attention was paid to longitudinal stability as envisaged by Pénaud. At the rear there was a horizontal tail that could be moved up and down by the pilot, more for adjusting balance in flight than for control, and there was also a vertical rudder for steering to the left or right.

For the maintenance of equilibrium in flight, Goupil had envisaged an extraordinary mechanism which he called a régulateur. This consisted of two vanes placed on outriggers at some distance from the body to the left and to the right and which could be moved in opposition to each other in order to re-establish the lateral position of the aeroplane if this, for any cause, were to become upset by an involuntary rolling movement. These vanes thus served as ailerons that were similar to those described by Boulton in his patent of 1868 and one is tempted to look for some relation between one and the other but it is hardly likely that a French engineer in 1884 would have reviewed all the English patents of 15 years before.

Apart from their aileron effect, these vanes could also move in conjunction and served as elevons to act on the longitudinal position in flight. The régulateur was actuated by a heavy pendulum that worked in conjunction or in opposition and therefore served as a system for automatically maintaining balance during flight.

Goupil’s essay ended with the statement that flying machines would be cumbersome as well as difficult to shelter and to garage but that these difficulties would probably not stop the coming of the fixed-wing aeroplane, and he has proved to be right.